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published by
the American Chemical Society
written by
Patti Galvan and
Jim Kessler

This multimedia lesson by the American Chemical Society explores how heating and cooling affect the motion of atoms in a solid. The inquiry-based lesson is supplemented by four interactive simulations that help students visualize particle configuration in solids and compare the molecular structure of solids and liquids. The classroom experiment uses a ball-and-ring apparatus to show expansion of a metal when heated. Included in the lesson is a student activity sheet with answer key and suggested discussion questions.

Editor's Note: The experiment may be done as a classroom lab or viewed as a video if the apparatus is unavailable to the teacher.

Standards (7)

AAAS Benchmark Alignments (2008 Version)

4. The Physical Setting

6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.

6-8: 4D/M3ab. Atoms and molecules are perpetually in motion. Increased temperature means greater average energy of motion, so most substances expand when heated.

6-8: 4D/M3cd. In solids, the atoms or molecules are closely locked in position and can only vibrate. In liquids, they have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. In gases, the atoms or molecules have still more energy and are free of one another except during occasional collisions.

6-8: 4D/M8. Most substances can exist as a solid, liquid, or gas depending on temperature.

6-8: 4D/M10. A substance has characteristic properties such as density, a boiling point, and solubility, all of which are independent of the amount of the substance and can be used to identify it.

11. Common Themes

11B. Models

6-8: 11B/M1. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.

6-8: 11B/M6. A model can sometimes be used to get ideas about how the thing being modeled actually works, but there is no guarantee that these ideas are correct if they are based on the model alone.

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